[Buildroot] [PATCH] system: add options for /bin /sbin and /lib to be symlinks into /usr

Yann E. MORIN yann.morin.1998 at free.fr
Thu Sep 3 23:47:42 UTC 2015


systemd is increasingly expecting things to live in /usr/bin or
/usr/sbin. It has inherited those expectations from a Fedora change:
    https://fedoraproject.org/wiki/Features/UsrMove

Note however, that systemd does support /usr being on a separate
filesystem; it just expects an initramfs to mount it before the final
switchroot over to the actual rootfs.

But the traditional use-case for Buildroot is not to boot with an
initramfs; although that is totally feasible, that's probably not what
is commonly done in the vast majority of cases.

However, a lot of packages still install stuff directly into /bin or
/sbin, which systemd may need early-on in the boot process, even before
it may have a chance to mount /usr. Even though we can tell systemd, at
configure-time, where it should expect programs to be at runtime, it
does not make sense to go head-first against an upstream wa^Hill.

Add an option so that /bin and /sbin be symlinks to /usr/bin and
/usr/sbin. Ditto for /lib for consistency. That option is forcibly
enabled when the init system is systemd.

Furthermore, this means we're no longer supporting a split-usr setup, so
the corresponding configure options have been removed as well for
systemd and, when using a merged /usr, for eudev as well.

Note: we need not handle /lib32 or /lib64, as they already are symlinks
to /lib, which means they will automatically be redirected to /usr/lib.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998 at free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
Cc: Arnout Vandecappelle <arnout at mind.be>
Cc: Mike Williams <mike at mikebwilliams.com>
Cc: Vicente Olivert Riera <Vincent.Riera at imgtec.com>
---
 package/eudev/eudev.mk       |  2 --
 package/skeleton/skeleton.mk | 20 +++++++++++++++++---
 package/systemd/systemd.mk   |  2 --
 system/Config.in             | 13 +++++++++++++
 system/skeleton/bin/.empty   |  0
 system/skeleton/lib/.empty   |  0
 system/skeleton/sbin/.empty  |  0
 7 files changed, 30 insertions(+), 7 deletions(-)
 delete mode 100644 system/skeleton/bin/.empty
 delete mode 100644 system/skeleton/lib/.empty
 delete mode 100644 system/skeleton/sbin/.empty

diff --git a/package/eudev/eudev.mk b/package/eudev/eudev.mk
index 1aa74b3..24fe4ed 100644
--- a/package/eudev/eudev.mk
+++ b/package/eudev/eudev.mk
@@ -22,11 +22,9 @@ EUDEV_CONF_ENV += LIBS=-lrt
 EUDEV_CONF_OPTS =		\
 	--disable-manpages	\
 	--sbindir=/sbin		\
-	--with-rootlibdir=/lib	\
 	--libexecdir=/lib	\
 	--with-firmware-path=/lib/firmware	\
 	--disable-introspection			\
-	--enable-split-usr			\
 	--enable-libkmod
 
 EUDEV_DEPENDENCIES = host-gperf host-pkgconf util-linux kmod
diff --git a/package/skeleton/skeleton.mk b/package/skeleton/skeleton.mk
index 48e7085..920d3b4 100644
--- a/package/skeleton/skeleton.mk
+++ b/package/skeleton/skeleton.mk
@@ -19,15 +19,29 @@ else
 SKELETON_PATH = system/skeleton
 endif
 
+ifeq ($(BR2_ROOTFS_MERGED_USR),y)
+define SKELETON_USR_SYMLINKS_OR_DIRS
+	ln -snf usr/bin $(TARGET_DIR)/bin
+	ln -snf usr/sbin $(TARGET_DIR)/sbin
+	ln -snf usr/lib $(TARGET_DIR)/lib
+endef
+else
+define SKELETON_USR_SYMLINKS_OR_DIRS
+	$(INSTALL) -d -m 0755 $(TARGET_DIR)/bin
+	$(INSTALL) -d -m 0755 $(TARGET_DIR)/sbin
+	$(INSTALL) -d -m 0755 $(TARGET_DIR)/lib
+endef
+endif
+
 define SKELETON_INSTALL_TARGET_CMDS
 	rsync -a --ignore-times $(SYNC_VCS_EXCLUSIONS) \
 		--chmod=u=rwX,go=rX --exclude .empty --exclude '*~' \
 		$(SKELETON_PATH)/ $(TARGET_DIR)/
-	$(INSTALL) -m 0644 support/misc/target-dir-warning.txt \
-		$(TARGET_DIR_WARNING_FILE)
+	$(SKELETON_USR_SYMLINKS_OR_DIRS)
 	ln -snf lib $(TARGET_DIR)/$(LIB_SYMLINK)
-	mkdir -p $(TARGET_DIR)/usr
 	ln -snf lib $(TARGET_DIR)/usr/$(LIB_SYMLINK)
+	$(INSTALL) -m 0644 support/misc/target-dir-warning.txt \
+		$(TARGET_DIR_WARNING_FILE)
 endef
 
 SKELETON_TARGET_GENERIC_HOSTNAME = $(call qstrip,$(BR2_TARGET_GENERIC_HOSTNAME))
diff --git a/package/systemd/systemd.mk b/package/systemd/systemd.mk
index b62fc08..59ab103 100644
--- a/package/systemd/systemd.mk
+++ b/package/systemd/systemd.mk
@@ -28,7 +28,6 @@ endif
 
 SYSTEMD_CONF_OPTS += \
 	--with-rootprefix= \
-	--with-rootlibdir=/lib \
 	--enable-static=no \
 	--disable-manpages \
 	--disable-selinux \
@@ -37,7 +36,6 @@ SYSTEMD_CONF_OPTS += \
 	--with-dbuspolicydir=/etc/dbus-1/system.d \
 	--with-dbussessionservicedir=/usr/share/dbus-1/services \
 	--with-dbussystemservicedir=/usr/share/dbus-1/system-services \
-	--enable-split-usr \
 	--disable-efi \
 	--disable-gnuefi \
 	--disable-tests \
diff --git a/system/Config.in b/system/Config.in
index fad829d..735ad62 100644
--- a/system/Config.in
+++ b/system/Config.in
@@ -88,6 +88,7 @@ config BR2_INIT_SYSTEMD
 	depends on BR2_USE_MMU
 	depends on !BR2_STATIC_LIBS
 	depends on BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_10
+	select BR2_ROOTFS_MERGED_USR
 	select BR2_PACKAGE_SYSTEMD
 
 comment 'systemd needs an (e)glibc toolchain, headers >= 3.10'
@@ -178,6 +179,18 @@ endif
 
 if BR2_ROOTFS_SKELETON_DEFAULT
 
+config BR2_ROOTFS_MERGED_USR
+	bool "Use symlinks to /usr for /bin, /sbin and /lib"
+	help
+	  If you say 'n' here, then /bin, /sbin and /lib and their
+	  counterparts in /usr will be separate directories. This
+	  is the historical UNIX way. In this case, /usr can be a
+	  filesystem on a partition separate from / .
+
+	  If you say 'y' here, then /bin, /sbin and /lib will be symlinks
+	  to their counterparts in /usr. In this case, /usr can not be a
+	  separate filesystem.
+
 config BR2_TARGET_ENABLE_ROOT_LOGIN
 	bool "Enable root login with password"
 	default y
diff --git a/system/skeleton/bin/.empty b/system/skeleton/bin/.empty
deleted file mode 100644
index e69de29..0000000
diff --git a/system/skeleton/lib/.empty b/system/skeleton/lib/.empty
deleted file mode 100644
index e69de29..0000000
diff --git a/system/skeleton/sbin/.empty b/system/skeleton/sbin/.empty
deleted file mode 100644
index e69de29..0000000
-- 
1.9.1




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